纯铜表面等离子喷焊 Ni 60 涂层组织及性能的研究

采用等离子喷焊工艺在纯铜基体表面成功制备了Ni60焊层,并对其微观形貌、元素成分、显微硬度及耐磨性能进行分析。分析表明:焊层与基体呈现良好的冶金结合,稀释率仅为5%左右,且其显微组织呈细小枝晶状,硬质相呈弥散分布,焊层显微硬度高达606HV,耐磨性能较Cu-Ni合金焊层提高了1倍。     

Phase Formation and Transformation in Alumina/YSZ Nanocomposite Coating Deposited by Suspension Plasma Spray Process

Suspension Plasma Spray process was used for deposition of pseudo-eutectic composition of alumina-yttria-stabilized zirconia as a potential thermal barrier coating using Mettech axial III torch. Process variables including feed and plasma parameters were altered to find their effects on the formation of phases in the composite coating. The in-flight particle velocity was found to be the crucial parameter on phase formation in the resulting coatings. Low particle velocities below 650 m/s result in the formation of stable phases i.e., α-alumina and tetragonal zirconia. In contrast, high particle velocities more than 750 m/s favor the metastable γ-alumina and cubic zirconia phases as dominant structures in as-deposited coatings. Accordingly, the plasma auxiliary gas and plasma power as influential parameters on the particle velocity were found to be reliable tools in controlling the resulting coating structure thus, the consequent properties. The noncrystalline portion of the coatings was also studied. It was revealed that upon heating, the amorphous phase prefers to crystallize into pre-existing crystalline phases in the as-deposited coating. Thus, the ultimate crystalline structure can be designed using the parameters that control the particle velocity during plasma spray coating.     

等离子喷涂石墨/氧化铝复合涂层微观结构及介电性能研究

以石墨为吸收剂,氧化铝为填料,聚乙烯醇为粘结剂,利用喷雾干燥法制备了石墨/氧化铝粉末,通过等离子喷涂工艺制备了石墨/氧化铝复合涂层,分析了涂层的相组成和微观结构,讨论了石墨含量对涂层微观结构和介电性能的影响.结果表明:喷涂后的涂层中有新相AlN(氮化铝)生成.涂层的密度和孔隙率与石墨含量有关,随着石墨含量的增加,涂层的密度逐渐减小,而孔隙率逐渐增加.介电性能测试表明,涂层的介电常数和介电损耗均随石墨含量地增加而增大.     

等离子喷涂Ni基WC涂层的组织与性能研究

利用等离子喷涂的方法在45钢基体上喷涂Ni基WC涂层;并研究了涂层的显微组织、硬度、耐磨性。结果表明:涂层组织致密与基体结合良好,喷涂中WC颗粒部分分解形成W2C,同时生成新的硬质相和共晶组织。涂层中包含了W2C、Ni3B、Cr7C3、Cr23C6和(Fe,Ni)23C6等化合物,有效地改善了涂层的性能。     

短切SiCf/LAS复合材料的显微结构与介电性能

采用热压烧结法制备出致密的短切SiC_f增强LAS玻璃陶瓷复合材料,并讨论保温时间与热压压力对复合材料介电性能的影响.结果表明,测试频率在8～12 GHz之间,复合材料复介电常数实部ε′由基体的7.6上升到10～100,虚部ε″由基体的0.34上升到40～160,介电损耗tgδ由基体的0.04上升到1～20,并具有明显的频散效应.随保温时间的延长或热压压力的提高,复合材料ε′增大,ε″与tgδ减小.此外,断口形貌的SEM观察表明,随保温时间的延长或热压压力的提高,复合材料界面层变厚.     

不锈钢表面冷喷涂铜涂层组织和性能研究

采用冷喷涂技术在不锈钢表面喷涂纯铜涂层;涂层的断面形貌和硬度分别通过光学金相显微镜观察和显微硬度计测试,同时研究了涂层的结合机理.结果表明,粉末在沉积过程中存在低速粒子,部分低速粒子沿原路径反弹后影响其他粒子的沉积;纯铜涂层与基体的结合为机械结合;涂层内部兼有部分冶金结合;涂层的硬度分布较均匀,且高于纯铜的硬度.     

反应等离子喷涂TiN/AlN涂层在润滑状态下摩擦磨损性能的研究

对用反应等离子喷涂法制备的TiN／AlN涂层在油润滑条件下的摩擦磨损特征进行了研究，并就轻、重载荷下的磨损机理进行了探讨。结果表明：油润滑条件下，涂层磨损体积显著降低。在轻载荷下，以疲劳磨损为主；在重载荷下，以脆性剥落和磨粒磨损为主。     

Plasma Sprayed Coating Using Mullite and Mixed Alumina/Silica Powders

Plasma sprayed ceramic coatings are widely used for thermal barrier coating applications. Commercially available mullite powder particles and a mixture of mechanically alloyed alumina and silica powder particles were used to deposit mullite ceramic coatings by plasma spraying. The coatings were deposited at three different substrate temperatures (room temperature, 300?°C, and 600?°C) on stainless steel substrates. Microstructure and morphology of both powder particles as well as coatings were investigated by using scanning electron microscopy. Phase formation and degree of crystallization of coatings were analyzed by x-ray diffraction. Differential thermal analysis (DTA) was used to study phase transformations in the coatings. Results indicated that the porosity level in the coatings deposited using mullite initial powder particles were lower than those deposited using the mixed initial powder particles. The degree of crystallization of the coatings deposited using the mixed powder particles was higher than that deposited using mullite powder particles at substrate temperatures of 25 and 300?°C. DTA curves of the coatings deposited using the mixed powders showed some transformation of the retained amorphous phase into mullite and alumina. The degree of crystallization of the as sprayed coatings using the mixed powder particles was significantly increased after post deposition heat treatments. The results indicated that the mechanically alloyed mixed powder can be used as initial powder particles for deposition of mullite coatings instead of using mullite powders.     

反应等离子喷涂TiN/AlN涂层在润滑状态下摩擦磨损性能的研究

对用反应等离子喷涂法制备的TiN/AlN涂层在油润滑条件下的摩擦磨损特征进行了研究,并就轻、重载荷下的磨损机理进行了探讨。结果表明:油润滑条件下,涂层磨损体积显著降低。在轻载荷下,以疲劳磨损为主;在重载荷下,以脆性剥落和磨粒磨损为主。     

等离子喷涂纳米FeS-SiC复合涂层的显微结构研究

以自制的纳米FeS-SiC复合粉末为原料，采用等离子喷涂技术制备了纳米结构FeS-SiC复合涂层。纳米粉末及涂层的形貌、成分、结构和物相组成分别由SEM，EDS，XRD表征。实验结果表明，纳米FeS-SiC复合粉末经造粒后的颗粒尺寸分布在20-80μm，流动性好，适于等离子喷涂。等离子喷涂纳米FeS-SiC复合涂层的晶粒呈现两种尺寸分布，一种是30．80nm的小晶粒，另一种是100-200nm的大晶粒。涂层的物相主要由FeS和SiC组成，还含有少量的Fe1-xS和氧化物。涂层的气孔率大约为19％。     

冷喷涂单颗粒铜在铝基体上的显微结构研究

采用冷喷涂法在铝(Al)基体上沉积单颗粒铜(Cu),利用聚焦离子束/电子束(FIB/SEM)系统精确定位并原位制备了完整单个颗粒Cu沉积在Al基体上的透射样品,分析其显微结构及形成原因。实验结果表明,撞击过程中温度与应力分布不均匀,导致沉积Cu颗粒不均匀形变。Cu/Al界面受影响较大:颗粒动能转化为形变能和热能,打破了界面处氧化膜,使界面附近温度迅速升高,发生动态再结晶,生成金属间化合物Cu_9Al_4;Cu颗粒内距界面越远的区域,受温度和应力的影响越小,其变形主要是通过晶体内位错增殖和移动;沉积颗粒顶部,远离Cu/Al界面,几乎不受应力和温度影响,保持原始显微结构。     

等离子喷涂工艺参数对Cr_2O_3涂层组织和磨损性能的影响

通过改变PLC控制的等离子喷涂工艺参数,研究了喷涂电流、电压、氩气流量和喷涂距离对Cr2O3涂层磨损性能和显微组织的影响。结果表明,Cr2O3粉末喷涂的最佳电流、氩气流量、电压和喷涂距离分别为450 A、45 L/min、60 V和90 mm。纳米级Cr2O3涂层形成了片状组织和纳米颗粒的混合结构,有利于涂层耐磨性和韧性的提高。     

Influence of the Surface State on the Adherence of the Coating: Case of an Alumina Coating Plasma Sprayed on SiC Composites

In thermal spraying, adherence between the coating and the substrate appears as the fundamental point. To favor a good interaction between both, it is often necessary to clean and prepare the substrate surface. Conventionally, solvents and sand blasting are applied to remove the contaminants and increase the surface roughness for a mechanical anchorage. However, according to the substrate nature (ceramic) or the substrate morphology, it can be prejudicial to apply a mechanical treatment because of peeling of the surface or a decrease in the global properties. Then, to obtain an appropriate preparation, several techniques can be investigated, such as water jet, ice blasting, and heat treatment; as well, laser ablation can be an interesting technology to prepare the substrate surface. The aim of this work was to study the modifications induced by 10 ns single or cumulative pulses of a Q-switched Nd:YAG near-infrared laser and its influence on the interface adhesion. The case of an alumina coating sprayed on a ceramic matrix composite (CMC) was studied. In these conditions, the laser treatment seems favorable from the adherence viewpoint according to the mechanical effect (induced by a conelike structure) and the chemical effect.     

C/C复合材料表面CoNiCrAlTaHfY/Co复合涂层的组织

在H2+Ar等离子刻蚀后的C/C复合材料表面进行等离子渗Co和CoNiCrAlTaHfY共渗复合处理,形成CoNiCrAlTaHfY/Co多元复合涂层,通过与刻蚀前后制备的CoNiCrAlTaHfY涂层对比分析,研究了刻蚀与Co过渡层对CoNiCrAlTaHfY/Co复合涂层组织、成分及结合强度的影响。结果表明,刻蚀前、后形成的CoNiCrAlTaHfY涂层厚度分别为10μm和14μm。刻蚀处理后,原棒状炭纤维与紧密包裹其的碳基体分别被刻蚀成针状和薄壁管,在炭纤维与基体碳之间形成孔隙,比表面积也相应增大,促进元素形核和扩散,使涂层与基体结合强度增加。在刻蚀表面与CoNiCrAlTaHfY多元涂层间增加Co过渡层,形成的CoNiCrAlTaHfY/Co复合涂层厚约30μm,复合涂层成分连续,组织均匀致密,由CrCoTa,Al2Ta,Cr2Ta,Alx Cry,Al Co2Ta,Co,AlxNiy组成,Co过渡层与CoCrAlTaHfYNi表层分别以三维岛状和柱状生长。CoNiCrAlTaHfY表层/Co过渡层/基体间的互扩散导致涂层与基体间的结合力明显提高。     

Mo元素掺杂对氧化铝基陶瓷/金属复合材料微观形貌及介电性能的影响

采用粉末冶金法制备了Mo掺杂的Al_2O_3基陶瓷/金属复合材料(Al_2O_3/Mo),利用X射线衍射、扫描电镜等测试分析方法研究了Mo掺杂对复合材料微观形貌及介电性能的影响。结果表明:Al_2O_3/Mo复合材料主要由Al_2O_3相和Mo相组成,未出现新相。Mo主要分散在Al_2O_3晶界,并且随着Mo掺杂量的增加,Al_2O_3晶粒尺寸逐渐减小、材料气孔率逐渐增加。当Mo掺杂量小于20%(质量分数)时,复合材料电阻率(10~(12)?·cm)与相对介电常数(8~9)没有明显变化;而当Mo掺杂量大于20%,Mo由弥散相转变为连续相,复合材料的体电阻率急剧下降到10~(10)?·cm;当Mo掺杂量达到40%时,由于复合材料中Mo已经形成连续的贯穿网络,体电阻率下降趋势减缓,稳定在10?·cm左右。因此,通过调控Al_2O_3基体中的Mo掺杂量及相分布,可以制备出具有不同电阻率的陶瓷/金属复合材料。     

摩擦喷射复合电沉积MoS2/Ni镀层结构与性能研究

利用摩擦喷射复合电沉积工艺在钢基材料上制备MoS2/Ni减摩复合镀层,观测分析了镀层形貌结构,并对其性能进行测试.研究表明,MoS2加入到镍镀层后,能显著改善镀层摩擦学性能,相同测试条件下,摩擦因数为同工艺纯镍镀层的1/4,磨损失重也仅为纯镍镀层的13 %.复合镀层磨损形式为磨粒磨损,除了有个别较浅、较窄磨痕之外,磨损表面较为光滑,没有出现粘着现象.     

脉冲电流下的热喷涂层组织演变

对A3钢基材表面的热喷涂层进行脉冲电流处理,通过显微镜观察涂层组织结构变化,结果表明,在脉冲电流处理下涂层组织结构发生了变化,涂层所固的层状结构趋于愈合。     

60Si2Mn钢等离子喷焊快速成形组织及性能研究

将等离子喷焊技术与快速成形技术相结合,实现了金属零件的直接成形。研究表明,等离子喷焊技术具有工艺流程少、成形速度快、设备简单等特点;在一定的焊接工艺条件下,喷焊层组织晶粒细小、均匀且晶界明显,喷焊层的显微组织为马氏体和残余奥氏体,类似于60Si2Mn钢淬火后组织,喷焊层显微硬度分布均匀,在590～630HV之间,力学性能好。     

电弧喷涂Ti6Al4V涂层的组织与耐蚀性能研究

采用电弧喷涂技术在Q235钢基体上喷涂Ti6Al4V涂层,并对涂层进行封孔处理.表征了涂层的物相组成和微观形貌,通过盐水浸泡实验和极化曲线测试对比分析了Q235钢基体、未封孔涂层和封孔涂层的耐腐蚀性能.结果表明:涂层呈典型的层状特征,物相组成为TiN,TiO和少量的Ti;未封孔涂层与封孔涂层均具有较宽的钝化电位区间,封...